Nowadays light has become a contributing factor to the comfort of rooms and a contributing factor in energy saving concepts in facility management. Stringent requirements are therefore placed on modern lighting systems both in terms of their functionality and in terms of their energy efficiency.
Recent lighting systems have in the meantime been realized predominantly with the aid of so-called DALI operating devices. DALI itself is an interface definition for digital standardized communication (IEC 62386) between lighting control components and electronic control gear (ECG) for different luminous means. The communication between control devices and ECG in this case takes place via a two-wire line. An essential feature of a DALI system is the addressability of the ECGs, i.e. the control gear are generally connected to one and the same two-core control line, but, after the assignment of an individual address, can be driven separately
or split into separately controllable groups. In a DALI system, only control components should always automatically transmit commands on this line; they are “masters” in a DALI system. On the other hand, ECGs do not produce any commands, but should only respond to a query from a master. ECGs are therefore so-called “slaves”.
Specifically, the query is made to the ECG as follows:
The master transmits any desired query, for example “luminous means defect?”, to one or more ECGs and expects a response directly after transmission of the query within a very short defined time window. Outside this time window, responses are rejected as being invalid.
The query by the master can take place, as is also the case for other DALI commands, at any desired time, which means that the ECGs must always be communication-ready. The ECGs therefore need to be continuously supplied with energy. This applies in particular also when the luminous means of an ECG has been switched off by a DALI command and is in the standby mode.
The above described permanent energy supply to ECGs results in a high, undesired energy consumption in the standby mode, in particular in the case of large lighting systems.
In order to reduce the energy consumption in the standby mode, relatively large lighting systems are isolated from the power supply system manually or via time switches when it is ensured that they are not required (for example at night time). During conventional usage times of the system,
however, all of the system components are supplied with energy from the power supply system. Unused system components are then in the standby mode and thus cause an undesirable additional energy consumption.
Manual isolation of the lighting system from the power supply system, or isolation controlled via time switches, as has previously been practiced, in order to save energy also has the disadvantage that the lighting system can only be activated by additional working steps, if said lighting system is required in an exception case during this time.